1. Field of the Invention
This invention relates to the field of door-latch openers, particularly door-latch openers of the type used in hospitals and similar facilities having push and/or pull-type actuation. More particularly this invention relates to push and pull-type actuated door-latch openers having fire safety locks.
2. Description of Related Art
Push-type door-latch openers and pull-type door-latch openers are now in common use in hospitals and other facilities where normal rotationally activated door-latch openers are undesirable for one reason or another. In typical application a pull-type door-latch opener will be mounted on the side of a door toward which the door opens and a push-type door-latch opener will be mounted on the opposite side thereof. In this manner, one motion control of the door is achieved.
Door-latch openers according to the present invention operate a door-latch mechanism which comprises a door bolt biased into the latched position by a spring. The door may be unlatched so that it may be opened by moving the latch back into the door against the bias. This function is performed by a door-latch opener. The door-latch opener operates a lever arm which moves the latch back into the door allowing the door to be opened.
Push-type door-latch openers are typically used in doors along corridors in hospitals where doors open into rooms from the corridor. Door-latches used in these environments should have the feature of being push-operated from the corridor and pull-operated from the room. Door-latches used in these environments are typically required to have a fire override feature or fire-safety lock which inhibits push-operation from the corridor under fire conditions. The fire-safety lock should, for example, prevent the blast of water from a fire hose operated in the corridor from activating the push-latch and opening the door.
Push-type door-latch openers of the prior art are described, for example, in U.S. Pat. No. 4,003,593. Although fit for their intended purposes, such door-latch openers have sometimes proven difficult to install in all of their various configurations, lack adequate biasing of the door handle under certain circumstances and the pull and push versions of the door-latch openers have had less than an optimal number of common parts.